The ship always seemed like an easier version of this puzzle - I would say that yes, they are both the same object, in the same way that they would be if time travel was involved (e.g. if today's ship is sitting in the harbour next to last week's ship).
I'm not so sure it is analogous to time travel. In a time travel example a continuous link could be traced between the two bodies, thus showing them to be the same thing (the earlier body will become the later one which has been the earlier one). However there is no such direct continuation between ship reconstructed from the original pieces, and the ship made of new pieces.
I would suggest the question "is the information content the same, or a superset of the information content the item in question possessed the last time it was examined?"
Hmmm, interesting approach. But don't you then have the problem that if you hack the ship's mast off it loses the information contained in the mast and thus becomes a different ship?
I don't think the mast contains any useful information. I may be drifting from the information-theoretic definition of the word now though. Perhaps we need a new term, analogous to energy:
Q. What is energy? A. Something that is conserved during physical processes - it doesn't really exist but we claim it does because it's useful.
Q. What is quintessence? A. That which makes an item what it is - it doesn't really exist but we claim it does because it's useful.
Quintessence is like information, but weighted by the importance that is placed on the information content of a component. eg I don't think that the information content of the mast of a ship is important at all in the general case, so its loss doesn't alter the quintessence of the ship. If a particular mast has survived deadly storms, then perhaps the sailors would start ascribing importance to it, saying things like "the old girl wouldn't be the same ship without it". In which case I rest mine. ;-)
That's just like saying that an ice-axe is its handle - what if you replace the smaller "important" bit of ship piece-by-piece?
The quintessence idea is more interesting, however. We could think of an item's quintessence as being removed by damage, and slowly recharging with experience - if the new mast survived many storms, say, it could grow to be an important part of the ship in its own right. However, if too much is removed at once the ship's quintessence drops too low, and it can no longer be considered the same ship.
Energy - are you aware of Noether's Theorem? Essentially, symmetries of a physical theory are in one-to-one correspondence with conserved quantities. Conservation of energy is equivalent to time-invariance of Newtonian physical laws, conservation of momentum is equivalent to position-invariance, etc. Of course, it's more general than that, and holds in non-Newtonian cases - I believe conservation of the stress-energy tensor is given by Noether's theorem and relativity's invariance under diffeomorphisms of
( ... )
There is an absolutely lovely monologue held by The High King in The Fifth Elephant by Terry Pratchett, where, upon being asked by Commander Vimes about the Scone of Stone being cast in Ankh-Morporkian clay, he explains the consistency of the Scone regardless of the actual matter in terms of his family axe. The axe, as it were, has needed replacement of the blade, and replacement of the handle, and added decorations, and engravings, but is this not my father's axe regardless of these minor fixes?
You should read it. It's a lovely exposition. And it's Pratchett!
I'd forgotten that bit - it's been far too long since I read The Fifth Elephant. Dammit, I must re-read some Pratchett, but almost all of my Pratchett books are in Oxford!
In terms of human identity, I think the first differential (if you like) of the information in a person is at least as important as the static information
( ... )
Re: TransitionspozorvlakMarch 24 2006, 14:54:06 UTC
Now that is interesting. I'm reminded of the Zetetic Elench in Iain M. Banks' book Excession who try to embrace every new experience and be changed by it, to the extent that if you meet an Elencher again after some years apart, you're expected to treat them as an entirely new person.
Comments 15
If you replace the ship a piece at a time, until none of the original pieces remain is it the same ship?
If you then put the old pieces back together, is it the same ship?
If they are both the same ship then do you have the same ship in both places at once?
Intruiging...
And then there's the question of what happens if you swap half of your brain with half of someone else's brain... Then who's who?
E
x
Reply
Reply
E
x
Reply
Reply
Reply
Q. What is energy?
A. Something that is conserved during physical processes - it doesn't really exist but we claim it does because it's useful.
Q. What is quintessence?
A. That which makes an item what it is - it doesn't really exist but we claim it does because it's useful.
Quintessence is like information, but weighted by the importance that is placed on the information content of a component. eg I don't think that the information content of the mast of a ship is important at all in the general case, so its loss doesn't alter the quintessence of the ship. If a particular mast has survived deadly storms, then perhaps the sailors would start ascribing importance to it, saying things like "the old girl wouldn't be the same ship without it". In which case I rest mine. ;-)
Reply
The quintessence idea is more interesting, however. We could think of an item's quintessence as being removed by damage, and slowly recharging with experience - if the new mast survived many storms, say, it could grow to be an important part of the ship in its own right. However, if too much is removed at once the ship's quintessence drops too low, and it can no longer be considered the same ship.
Energy - are you aware of Noether's Theorem? Essentially, symmetries of a physical theory are in one-to-one correspondence with conserved quantities. Conservation of energy is equivalent to time-invariance of Newtonian physical laws, conservation of momentum is equivalent to position-invariance, etc. Of course, it's more general than that, and holds in non-Newtonian cases - I believe conservation of the stress-energy tensor is given by Noether's theorem and relativity's invariance under diffeomorphisms of ( ... )
Reply
You should read it. It's a lovely exposition. And it's Pratchett!
Reply
Reply
Reply
Reply
Reply
Leave a comment